A French woman who left her baby daughter to drown on a beach blamed “witchcraft” when she went on trial for murder on Monday.

Fabienne Kabou, 39, who was described as having “remarkable intelligence … but subject to irrational beliefs”, travelled to Berck-sur-Mer with her only child, Adélaïde, in November 2013.

Kabou checked into a hotel and asked locals about the tides before reportedly breastfeeding the child on the beach that night and leaving her as the sea came in and temperatures dropped to below freezing. The girl’s body was discovered by a prawn fisherman the following day.

A court artist’s sketch of Fabienne Kabou on the first day of her trial. Photograph: Benoit Peyrucq/AFP/Getty Images

Kabou told police she had chosen the town, on France’s Channel coast between Calais and Dieppe, because “even the name sounded sad”. Berck sounds like “yuck” in French.

According to French press reports, Kabou told investigators she walked on to the beach in the moonlight. “I stopped at one point. She gave a small jump as if she’d just woken up. She was looking for my breast, I gave it to her. I remained standing and I clutched her against me and then, I don’t know, I said: ‘No, no, no.’ I couldn’t stop saying ‘no’, I don’t know why. I cried. It was as if I was saying to someone: ‘I can’t do something like that,’ but I did it.”

She continued: “I saw the spray and I must have left Ada at five metres, perhaps two. In any case, she would have drowned straight away. I don’t know how fast the tide came in but it was very close. I put her down, I spoke to her, I told her I was sorry. She was fine, I think. She didn’t feel in danger, I was next to her, on my knees. I gave her a long hug … she wasn’t exactly asleep but she was calm … I don’t know how long I stayed there, saying I was sorry, talking to her. Then I turned on my heels and I ran.” The next day Kabou returned to Paris by train.

Kabou, of Senegalese origin, told the court of her well-off childhood in Dakar. She was described as a brilliant student. She is said to have an IQ of 130, well above average. She moved to France in 1995, where she abandoned an architecture course after two years and embarked on a philosophy degree. She also fell in love with a painter and sculptor 30 years her senior, Michel Lafon.

She terminated two pregnancies before giving birth to Adélaïde alone at the art studio she shared with Lafon. She had not consulted a doctor during the pregnancy and neither parent registered the birth with the authorities, so there was no official record of Adélaïde, who was named after her grandmother.

Kabou told detectives she heard voices persecuting her and evil forces that drove her to kill her daughter.

“In 2011 I fell pregnant with Adélaïde, she was born in August and I ended up killing her 15 months after her birth,” she told the court in the north-eastern town of Saint-Omer.

“Witchcraft. That’s my default explanation because I have no other.”

Kabou said she had spent around €40,000 consulting “witchdoctors and healers” before leaving the child to die on the beach.

“Nothing makes sense in this story. What interest could I have I have in tormenting myself, lying, killing my daughter? I spoke of sorcery and I’m not joking. Even a stupid person would not do what I did.”

Kabou’s lawyer Fabienne Roy-Nansion asked her to explain the evil forces she felt had driven her to kill.

“For many years I struggled to wake up in the morning. My feet were paralysed. I had hallucinations, like seeing the walls that wouldn’t stop shaking,” Kabou said.

Court psychiatrist Paul Bensussan said her act was possibly triggered to post natal depression. The father took no interest in the child, according to court documents.

Kabou is on trial for premeditated murder and faces life in prison if convicted. The trial in Saint-Omer is expected to last a week.